Coumarin conjugated SPION for molecular imaging.

Superparamagnetic iron oxide nanoparticles (SPIONs) with their distinct magnetic characteristics, biocompatibility, and ability to interact with biomolecules makes them the most sought after candidates for MRI contrast. However, their systemic distribution restricts their ability for enhancing the contrast at desired sites. We have functionalised the SPION with coumarin, a known anti-cancer agent, and studied it's in vivo behaviour using the 99mTc radiolabelling to enhance target specificity. We have exploited coumarin as a targeting moiety as it has already demonstrated its efficacy as an anti-cancer agent. In this study, we synthesise nanoparticles of iron oxide using the co-precipitation method and functionalised their surfaces were with 3-aminopropyl trimethoxysilane (APS) and then conjugated it to coumarin for tumour specificity. TEM images showed the size ranging from 50 nm to 100 nm and some aggrgation. Coating of APS on nanoparticles and further conjuagtion to coumarin was confirmed by FTIR, NMR and Mass spectroscopy. The in-vivo evaluation was done using the 99mTc radiolabelling and Gamma scintigraphy. An enhanced accumulation at the tumour site was observed; however, high uptake was also seen in the reticuloendothelial system. Gamma Scintigraphy showed accumulation of nanoparticles in the tumour region in the right hind leg a hepatobiliary clearence and aggregation in the liver and spleen (RES). These results thus suggest that coumarin, a suitable fluorescent probe, also improves the targeting of the SPION to the tumour site. The synthesised conjugate has the possibility of being used as a dual imaging probe. [ABSTRACT FROM AUTHOR]